Mixed convection boundary-layer flow near the stagnation-point on a vertical surface in a nanofluid

Abstract

The steady boundary layer flow of a nanofluid near a stagnation point on a vertical surface is investigated. The velocity of the external flow is assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically using the Keller box method with the help of MATLAB software. The effects of the Brownian motion parameter, thermophoresis parameter, and Lewis number on the fluid flow, heat and mass transfer characteristics are analyzed and discussed. It is found that for assisting flow, the friction at the surface decreases with an increase in Lewis number while it decreases with increasing Brownian motion and thermophoresis parameters. However, the effects of Lewis number for the opposing flow showed a different trend. Moreover, increasing the Brownian motion parameter, the thermophoresis parameter and the Lewis number are to decrease the heat transfer rate at the surface for both assisting and opposing flows, but on the other hand increase the mass transfer rate at the surface.